The gang discusses two papers that look at changes in teeth through time. The first paper looks at the earliest example of heterodont teeth in tetrapods, and the second paper looks at how different mammal groups build sabre tooth morphologies. Meanwhile, James has unique ideas for building worker morale, Amanda accidentally makes a pie faux pas, and Curt is friend to gelfling.

Up-Goer Five (Amanda Edition):

Today our friends talk about teeth. Wow, teeth is one of the ten hundred most used words. Cool. So some things have teeth that are all the same kind. Most of the very early things with four feet that go on long have teeth of all the same kind. But there is an early thing with four feet that goes on land that we have known about for a long time that was never really looked at too close and now we see that it has teeth that are big and round and teeth that are small and pointed. It was probably eating things that were very hard and needed to be broken up before it could eat them. What is cool is that there are lots of animals from the same place at the same time that also show this kind of eating thing, where they must have been eating things that were very hard like rock and had to be broken up before they could be eaten. Our friends also talk about animals with hair that had very very long pointed teeth in the front of the mouth. It turns out that these teeth grow in a very different way. Animals with hair only grow teeth two times, and the back teeth only grow in one time. Usually the back teeth grow in last. But these animals had their very very long pointed front teeth grow in last. And they grow in funny. They grow in along the inside of the old teeth, until they are as much as the old teeth, then the old teeth fall out. This might mean that these teeth show up in different animals with hair totally on their own over and over and over again many times, which is cool.

References:

Clack, Jennifer A., et al. "Acherontiscus caledoniae: the earliest heterodont and durophagous tetrapod." Royal Society open science 6.5 (2019): 182087. 

 Wysocki, Matthew Aleksander. "Fossil evidence of evolutionary convergence in juvenile dental morphology and upper canine replacement in sabertooth carnivores." Ecology and Evolution (2019). 

The gang discusses two papers that use large data sets to look at big picture patterns in evolution and ecology. Specifically, they look at one paper that explores brachiopod shell thickness in relationship to environmental preferences during the Late Ordovician mass extinction, and another paper that looks at the evolution of using the tail as a weapon in vertebrates. Meanwhile, James is eternally “young”, Curt invents unique ecological roles for Stegosaurus, and Amanda enables the worst type of ASMR (for those who cannot handle food sounds in microphones, skip 47:57-48:54).

Up-Goer Five (Curt Edition):

Our friends talk about two papers that bring together a lot of facts about things to say something about how living things have changed over time. The first one looks at hard rock like things that take food out of the water. This paper looks at how thick the hard parts of these things were and it focuses on a time when these things went through a real bad time and a lot of them died. While the paper finds a lot of interesting things, one of the big things they find is that some of the animals that pull food out of the water all made really thicker hard parts than the other types of animals that pull food out of the water. These animals that made really thick hard parts were also the ones that were hurt when a real bad time happened.

The second paper looks at animals that have a long part coming off their bottom. This paper looks at animals which use the long part on their bottom to hit things. There are lots of different ways animals with long parts coming off their bottom can use that long part to hit things, and this paper looks to see what parts need to be in place in order to have these animals be able to hit things. It turns out that there have been many times that life has found a way to hit things with a long part coming out of the bottom.

References:

 Arbour, Victoria M., and Lindsay E. Zanno. "The evolution of tail weaponization in amniotes." Proceedings of the Royal Society B: Biological Sciences 285.1871 (2018): 20172299. 

 Balthasar, Uwe, et al. "Brachiopod shell thickness links environment and evolution." Palaeontology (2019).